COPRODUCTION OF HIGH-PURITY ISOBUTANE AND BUTANE-1 FROM MIXED C4S

Abstract

The systems and processes described can be used to produce a high-purity isobutane stream and a high-purity 1-butene stream from mixed C4 streams having disparate starting compositions.

Description

COPRODUCTION OF HIGH-PURITY ISOBUTANE AND BUTANE-1 FROM MIXED C4S FIELD OF INVENTION The achievements in this report relate to procedures and systems for the co-production of 1-isobutane and 1-butene. BACKGROUND OF THE INVENTION Several procedures for producing a high-purity isobutene stream from a mixed C4 stream have been disclosed. Many of these involve esterifying the isobutene to produce methyl tert-butyl ether (MTBE), which can be separated from the remaining C4 and then cracked again to form a pure isobutene stream. Such procedures can be disclosed, for example, in US5628880 and US5321163, among others. The separation of isobutene in the form of MTBE allows the separation and recovery of butenes (1-butene and 2-butene). BRIEF DESCRIPTION OF THE INVENTION To the inventor's knowledge, no prior procedure has been provided for the co-production of a high-purity isobutane stream and a high-purity 1-butene stream. In one aspect, the embodiments described herein are directed toward a process for the co-production of high-purity isobutane and high-purity 1-butene streams. The process may include providing a first C4 mixed stream and a second C4 mixed stream, each comprising isobutene, isobutane, 1-butene, and 2-butene, wherein the first C4 mixed stream has a higher concentration of isobutane than the second C4 mixed stream. The first C4 mixed stream and methanol, as a reagent or selecting agent, may be fed to a first reaction system to convert the isobutene contained therein into methyl tert-butyl ether or isobutene dimers. The second C4 mixed stream and methanol, as a reagent or selecting agent, may be fed to a second reaction system to convert the isobutene contained therein into methyl tert-butyl ether or isobutene dimers.The process may then include separating an effluent from the first reaction system in a first separation system, including a water scrubbing system, to recover a first light hydrocarbon stream comprising 1-butene, 2-butene, and isobutane, a first methanol + water stream, and a first heavy hydrocarbon stream comprising methyl tert-butyl ether or isobutene dimers. Furthermore, the process includes separating an effluent from the second reaction system in a second separation system, including a water scrubbing system, to recover a second light hydrocarbon stream comprising 1-butene, 2-butene, and isobutane, a second methanol + water stream, and a second heavy hydrocarbon stream comprising methyl tert-butyl ether or isobutene dimers.The first and second streams of methanol and water can then feed a methanol recovery system to separate the methanol from the water and return at least some of the methanol to one or both of the first and second reaction systems. The second light hydrocarbon stream can feed a separation system to recover a stream containing isobutane, a 1-butene stream, and a first C4 heavy hydrocarbon stream comprising n-butanes and 2-butene. The stream containing isobutane and the first light hydrocarbon stream can feed a separation system to recover an isobutane stream and a second C4 heavy hydrocarbon stream comprising n-butanes and 2-butene. In another aspect, the achievements disclosed in this report refer to a system for the co-production of high-purity isobutane streams and High-purity 1-butene. The system may include a first mixed C4 feed stream and a second mixed C4 feed stream, each comprising isobutene, isobutane, 1-butene, and 2-butene. The first mixed C4 feed stream may have a higher concentration of isobutane than the second mixed C4 feed stream. The system also includes a first methanol feed stream and a second methanol feed stream. A first reaction system is configured to receive the first mixed C4 feed stream and the first methanol feed stream and to react the first mixed C4 feed stream with methanol, as a reagent or selecting agent, converting the isobutene contained therein into methyl tert-butyl ether or isobutene dimers.A second reaction system is configured to receive the second mixed stream of C4 and the second stream of methanol and to react the second mixed stream of C4 and the methanol, as a reagent or selecting agent, converting the isobutene contained therein into methyl tert-butyl ether or isobutene dimers.The system further includes a first separation system, which includes a water washing system, to separate an effluent from the first reaction system to recover a first stream of light hydrocarbons comprising 1-butene, 2-butene, isobutane, a first stream of methanol + water and a first stream of heavy hydrocarbons comprising methyl tert-butyl ether or isobutene dimers, as well as a second separation system, which includes a water washing system, to separate an effluent from the second reaction system to recover a second stream of light hydrocarbons comprising 1-butene, 2-butene, isobutane, a second stream of methanol + water, and a second stream of heavy hydrocarbons comprising methyl tert-butyl ether or isobutene dimers.A common methanol recovery system is provided to receive the first and second streams of methanol + water to separate the methanol from the water and a flow line to return at least some of the methanol to one or both of the first and second reaction systems; A first light hydrocarbon separation system is configured to receive the second light hydrocarbon stream and recover a stream containing isobutane, a 1-butene stream, and a first C4 heavy hydrocarbon stream comprising n-butanes and 2-butene. A second light hydrocarbon separation system is configured to receive the first light hydrocarbon stream and recover an isobutane stream and a second C4 heavy hydrocarbon stream comprising n-butanes and 2-butene. Other aspects and advantages will become evident from the following description and the attached claims. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a flow diagram of a simplified procedure of a system for the co-production of 1-butane and 1-butene according to the embodiments in this memoir. Figure 2 is a flow diagram of a simplified procedure of a system for the co-production of isobutane and 1-butene according to the embodiments in this memoir. Figure 3 is a flow diagram of a simplified procedure of a system for the co-production of isobutane and 1-butene according to the embodiments in this memoir. Figure 4 is a flow diagram of a simplified procedure of a system for the co-production of isobutane and 1-butene according to the embodiments in this memoir. DETAILED DESCRIPTION OF THE INVENTION The embodiments described herein relate to processes and systems for the co-production of isobutane and 1-butene. More specifically, the embodiments described herein are directed toward the production of high-purity isobutane and 1-butene streams from mixed C4 feedstocks. Even more specifically, the embodiments described herein are directed toward the simultaneous production of high-purity 1-butene and isobutane streams from a mixed C4 feedstock obtained from an RFCC / FCC and / or a steam cracking unit (SCU). Several upstream production processes can be used to generate C4 streams, such as fluid catalytic cracking (FCC) units, residual fluid catalytic cracking (RFCC) units, steam crackers, pyrolysis units (thermal cracking with or without steam), and various other mixed C4 production processes. The mixed C4 streams produced from these units may include isobutene, isobutane, 1-butene, 2-butene, n-butane, and butadienes, among other components. While they produce similar chemical compounds, these upstream C4 production systems result in streams with different compositional mixtures of the various C4 compounds. For example, mixed C4s from FCC or RFCC can have a much higher concentration of isobutane (>20 wt% or >25 wt%, for example) than a raffinate-1 recovered from a steam cracking butadiene production process (<5 wt% or <3 wt% isobutane, for example). At the same time, the concentration of isobutylene in FCC / RFCC C4s is much lower than for steam cracker C4s (such as <25 or 30 wt% for RFCC versus >35 or 40 wt% for steam cracker C4s). Likewise, each (FCC / RFCC versus steam cracker) may have a difference in the concentration of 1-butene (e.g., less than 20 or 15% by weight versus more than 35 or 40% by weight).Furthermore, the diene content of the FCC / RFCC mixed C4s is much higher than for the refined-1 steam cracker (such as 0.3% by weight or 3,000 ppmw versus 40 ppmw). Desiring to separate mixed C4s into several product streams, such as an isobutane stream and a 1-butene stream, a person skilled in the art could simply blend each of the various C4 streams for co-processing. However, the present inventors have found that, based on the differences in composition between the streams, these feedstocks must be processed separately in parallel reaction trains, including the common equipment that integrates the reaction trains, to produce the desired high-purity isobutane and high-purity 1-butene products. The use of parallel reaction trains provides for the recovery of raffinate streams—O4 streams mixed with effectively removed isobutene—from each reaction train and allows an operator to optimize the equipment size and associated utility consumption required for the purification of isobutane and 1-butene.The refining process from the FCC / RFCC reaction train will have a relatively higher concentration of isobutane and a lower concentration of 1-butene. In comparison, the refining process from the steam cracking reaction train will have a much higher concentration of 1-butene and a lower concentration of isobutane. In both reaction trains, isobutylene can be removed from the individual raffinate-2 streams through dimerization and / or conversion to methyl tert-butyl ether within the reaction trains (as used here, train 1 = C4 FCC / RFCC conversion, while train 2 = C4 conversion from the steam cracker). The reactor configuration in each train can be specific to the upstream C4 feed provided, tailored to meet the isobutylene conversion requirements. Furthermore, proper integration of product separations has been found to yield a high-purity isobutane stream. Although the C4 feed from the steam cracker has a comparatively low isobutane content, the additional isobutanes added to the FCC / RFCC raffinate streams provide a high-purity isobutane product stream. When the reaction system produces isooctene (isobutene dimers), the isooctene produced in both reaction trains can be combined, purified to remove oxygenated compounds, and then sent to a saturation reactor to convert the isooctane to isooctane, if desired. The isobutene dimers can also be used for alkylation. When the reaction system produces methyl tert-butyl ether (MTBE), the MTBE can be re-cracked to form a high-purity isobutene stream, for example. The reactor trains (train 1 and train 2) can use methanol as a reagent (to produce MTBE) or as a screening agent (for selective dimerization). The raffinate streams from each reactor train can be washed separately with water to remove the methanol. The resulting water / methanol streams can then be fed to a common methanol recovery system to allow for methanol recycling and wash water recycling. As previously mentioned, the configuration of reactor trains can be designed to provide efficiencies based on the C4 supply to the individual train. For example, a reactor train with a higher initial isobutene concentration can be processed in a single fixed-bed reactor or a series of fixed-bed reactors and may include an intermediate separation stage to remove a portion of the product (MTBE or dimer), thereby providing additional driving force for the continued conversion in the downstream reactors. When the initial isobutene concentration is lower, intermediate separations may or may not be used. In some embodiments, an upstream reactor effluent can be fed to a finishing reactor, which may be a catalytic distillation reactor, providing simultaneous reaction of any remaining isobutene and separation of the dimer product. MA / IZ / ¿U¿¿ / U41100 / MTBE of the remaining C4 components, including n-butane, 1-butane, 1-butene, and 2-butene. The catalyst in the catalytic distillation reactor may also have functionality for the selective hydrogenation of any butadiene present, thereby forming additional butenes. With reference to Figure 1, a flow diagram of a simplified procedure for a system for the co-production of isobutane and 1-butene, according to the embodiments described herein, is illustrated. A mixed C4 stream 10, having a relatively high concentration of isobutane, such as a C4 FCC or RFCC stream, can be fed to a first reaction train 12. The reaction train 12 can be used to convert the isobutene contained therein into MTBE or isobutene dimers (isooctene), including methanol 13 fed as a reagent or selecting agent. The reaction train 12, including internal separations (not shown), can produce a raffinate-2 stream 14, with little or no remaining isobutene, and a heavy stream (MTBE and / or isooctene) 16. Similarly, a mixed C4 stream 20, which has a relatively low concentration of isobutane, such as a C4 steam cracking stream, can be fed to a second reaction train 22. The reaction train 22 can be used to convert the isobutene contained therein into MTBE or isobutene dimers (isooctene), including methanol 23 fed as a reagent or screening agent. The reaction train 22, including internal separations (not shown), can produce a raffinate-2 stream 24, with little or no remaining isobutene, and a heavy stream (MTBE and / or isooctene) 26. Heavy streams 16 and 26, each containing MTBE or isooctene, can be combined to form a converted isobutene product stream 28. The dimers or ethers can be further processed (not shown), for example, by hydrogenation or subsequent cracking, among other possibilities, to produce a desired product. Stream 28 can also include heavy oxygenates byproducts. The raffinate stream 14 (from the first reactor train 12) may include various C4 components, such as isobutane, 1-butene, 2-butene, and n-butanes, and may be low in or contain no isobutene. The raffinate stream 14 may also include methanol and / or other oxygenated byproducts, such as dimethyl ether. The raffinate stream 14 may then feed a wash column with water 30 to remove the methanol, producing a water / methanol stream 32 and a mixed C4 stream 34. The raffinate stream 24 (from the second reactor train 22) may include various C4 components, such as isobutane, 1-butene, 2-butene, butadienes, and n-butanes, and may be low in or contain no isobutene. The raffinate stream 24 may also include methanol and / or other oxygenated byproducts, such as dimethyl ether. The raffinate stream 24 may then feed a wash column with water 40 to remove the methanol, producing a water / methanol stream 42 and a mixed C4 stream 44. The water / methanol streams 42, 32 can then feed a common methanol recovery system 50 for the separation of methanol from water. The recovered water (not shown) can be fed back into the water scrubbing systems 30, 40, and the recovered methanol can feed the methanol streams 13, 23 as a reagent or screening agent in the reaction trains 12, 22. Fresh methanol (not shown) can also be supplied within the methanol recovery system 50 or directly to the reactors where required within the reaction trains 12, 22. The mixed C4 stream 44, which has a relatively high concentration of 1-butene, can feed a separation system to recover a high-purity 1-butene stream. The 1-butene recovery system may include a heavy product column 60, which separates the 1-butene from the n-butane and 2-butene present. In some embodiments, a reaction zone (upstream or within the heavy product column 60, not shown) can be provided to isomerize 2-butenes to 1-butene. The heavy product column 60 can produce a C4 heavy hydrocarbon stream 62, which includes n-butane and 2-butene, and a high product stream 64, which contains isobutane and 1-butene.The high-flow stream 64 can then feed a light 1-butene column 70, where the isobutane and any dimethyl ether present can be recovered as overheads 72, and the 1-butene can be recovered as a final product 74, which can be a high-purity 1-butene stream, such as one having a 1-butene concentration above 90, 95, 98 or 99 wt%. The high-purity stream 72, containing isobutane from reaction train 2, and the mixed C4 stream 34, which has a relatively high isobutane concentration, can feed a separation system to recover a high-purity isobutane stream, such as one with an isobutane concentration greater than 90, 95, 98, or 99 wt%. The isobutane recovery system may include a deisobutanizer column 80, which separates the isobutane from any n-butane and 2-butene present. In some embodiments, a reaction zone (upstream or within the deisobutanizer column 80, not shown) can be provided to isomerize any 1-butene present to 2-butene. The deisobutanizer column 80 can produce a C4 heavy hydrocarbon stream 82, which includes n-butane and 2-butene, and an elevated stream 84 containing isobutane.The elevated stream 84 can then feed a light DME column 90, where the isobutane can be separated from any dimethyl ether present. The light DME can be recovered as elevated product 92, and the isobutane can be recovered as a bottoms product 94, which can be a high-purity isobutane stream. The C4 heavy hydrocarbon streams 62, 82, which include n-butane and 2-butenes, can be combined as a C4 heavy hydrocarbon stream 95 for further processing or recovery, as desired. For example, the n-butane and 2-butenes can be separated to provide a high-purity 2-butene stream. In some embodiments, the initial separation of isobutene can be by dimerization or etherification, as previously mentioned. Figures 2 and 3 illustrate a flow diagram of the simplified procedure for a system in which isobutene is separated by dimerization. While both systems achieve a similar end result and may include similar reactors, due to the different feed compositions, individual trains can be optimized for particular feed compositions or expected composition ranges. With reference to Figure 2, a flow diagram of the simplified procedure for reaction train 1 (high isobutane content) is illustrated. The mixed stream of C4 10 and methanol 13 can feed dimerization reactors 101 and 103, each of which contains a selective dimerization catalyst to convert isobutene to isobutene dimers. The effluent 104 from the first dimerization reactor 101 can be fed to the second dimerization reactor 103 for further isobutene conversion. The effluent 106 from the second dimerization reactor can then feed a catalytic distillation column 108 for further isobutene conversion while simultaneously separating the lighter C4 components that did not react with the desired dimer and any heavy oxygenated byproducts. Additional methanol 109 can be added to the catalytic distillation column 108, as needed.The lighter C4 components can be recovered as high fraction 110, while the dimer and heavy by-products can be recovered as bottom fraction 112. The lift fraction 110 may include 1-isobutane, 1-butene, 2-butene, and methanol, among other components. The lift fraction 110 can then feed a wash column containing water 120 for the separation of methanol from the C4 hydrocarbons. The wash water 121 can be fed to the top of the wash column containing water 120 and contacted countercurrently with the C4 hydrocarbons to remove the methanol. The C4 hydrocarbons can be recovered from the wash column containing water 120 as a lift fraction 122, and the methanol / water mixture can be recovered as a bottom fraction 124. With reference to Figure 3, a flow diagram of the simplified procedure for reaction train 2 (high isobutene content) is illustrated. The mixed stream of C4 20 and methanol 23 can be fed to a first dimerization reactor 201, which contains a selective dimerization catalyst to convert isobutene into isobutene dimers. The effluent 202 from the first dimerization reactor 201 can be fed to a debutanizer column 204 to separate the dimers 206 from the unreacted C4 components 208, which may be lower in isobutene compared to the feed stream 20 on a C4 basis. The high fraction 208 (unreacted C4) can then feed a second dimerization reactor 210 for further isobutene conversion. The effluent 212 from the second dimerization reactor can then feed a catalytic distillation column 216 for further isobutene conversion while simultaneously separating the lighter unreacted C4 components from the desired dimer and any heavy oxygenated byproducts. Additional methanol 218 can be added to the catalytic distillation column 108 as required. The lighter C4 components can be recovered as a high fraction 220, while the dimer and heavy byproducts can be recovered as a bottoms fraction 222. The lift fraction 220 may include 1-isobutane, 1-butene, 2-butene, and methanol, among other components. The lift fraction 220 may then feed a wash column containing water 230 for the separation of methanol from the C4 hydrocarbons. The wash water 232 may feed to the top of the wash column containing water 230 and come into countercurrent contact with the C4 hydrocarbons to remove the methanol. The C4 hydrocarbons may be recovered from the wash column containing water 230 as a lift fraction 234, and the methanol / water mixture may be recovered as a bottom fraction 236. The methanol / water streams 124 (Figure 2) and 236 can then be combined and fed to a common methanol recovery system 250. The methanol recovery system 250 can include distillation and / or membrane separations to separate the water from the methanol. As illustrated, distillation of the water / methanol mixture can produce a bottom water stream 260 and a boosted methanol stream 262. The water in the bottom water stream 260 can be returned to the wash water columns 230, 120 (Figure 2) via streams 232, 121, while the methanol in stream 262 can be fed to the various reactors (201, 210, 216, 101, 103, 108) as desired, such as via streams 13, 23. In some embodiments, the heavy streams (208, 222, 124 (Figure 2)), including the dimers and any heavy oxygenated byproducts, can be combined for further processing. In some embodiments, the heavy streams can be combined and separated in a distillation column 280 to recover a fraction of dimers 282 and a fraction of heavy oxygenated compounds 284, each of which can be processed and / or used in the fuel blend (as in gasoline, diesel, etc.). After the removal of isobutene through reaction and the generation of individual raffinate-2 streams in separate reactor trains, the mixed C4s can be separated to yield the desired isobutane and 1-butene product streams. Figure 4 illustrates the integrated isobutane and 1-butene purification zones, according to some embodiments in this document. The mixed C4 stream 234, which has a relatively high concentration of 1-butene, can be fed to a separation system to recover a high-purity 1-butene stream. The 1-butene recovery system can include a heavy product column 300, which separates the 1-butene from any n-butane and 2-butene present. The heavy product column 300 can produce a C4 heavy hydrocarbon stream 302, which includes n-butane and 2-butene, and a high product stream 304 containing isobutane and 1-butene. The high product stream 304 can then feed a light 1-butene column 310, where the isobutane and any dimethyl ether present can be recovered as overheads 312, and the 1-butene can be recovered as a bottoms product 314, which can be a high-purity 1-butene stream. The overhead stream 312, containing isobutane from reaction train 2, and the mixed C4 stream 122, which has a relatively high concentration of isobutane, can be fed to a separation system to recover a high-purity isobutane stream. The isobutane recovery system can include a deisobutanizer column 330, which separates the isobutane from any n-butane and 2-butene present. The deisobutanizer column 330 can produce a heavy hydrocarbon stream of C4 332, which includes n-butane and 2-butene, and an overhead stream 334 containing the isobutane. The overhead stream 334 can then be fed to a light DME column 340, where the isobutane can be separated from any dimethyl ether present. Light DME can be recovered as elevated 342, and isobutane can be recovered as a bottom product 344, which can be a high-purity isobutane stream.The heavy hydrocarbon streams of C4 302, 332, including n-butane and 2-butenes, can be combined as a heavy hydrocarbon product stream of C4 350. As described above, the embodiments in the present memory can be used to efficiently produce 1-isobutane and 1-butene products from various mixed C4 feed streams having disparate compositions. In some embodiments, the feed to each reaction train can be pretreated. As described below, a first reaction train can be used to process a C4 stream with a high isobutane content, and a second reaction train can be used to process a C4 stream with a low isobutane content, with some common systems integrating the two reaction trains. High isobutane streams, such as a C4 FCC or RFCC stream, will be fed to train 1, as described below, while low isobutane streams, such as a C4 stream from the steam cracker, will be fed to train 2, as described below. Train 1 Feed pretreatment C4 FCC / RFCC feedstocks can undergo feed pretreatment in a primary pretreatment system. The unsaturated mixed C4 feedstock from a countercurrent plant, such as an LPG plant, can be filtered and then washed in a water wash column using a countercurrent flow of demineralized wash water under flow control to remove most water-soluble impurities, such as nitriles. The top of the water wash column can be equipped with a mesh pad to merge and remove unseparated water. The spent wash water from the column bottoms can be sent for treatment in the refinery's wastewater system. The washed C4 mixture can then be taken from above the wash water column and sent under pressure control to the C4 feed compensation drum of train 1. The compensation drum can also be equipped with a smelter and a water boot to remove any remaining free water. Should a small amount of non-condensable vapors accumulate in the compensation drum, a pressure venting system with an associated nitrogen purge can be provided to dilute and vent these vapors to the flare. The washed C4 feedstock can then be pumped from the compensation drum and sent to the primary reactor of train 1. Train 2 Feed pretreatment The C4 from the steam cracker, or C4 as a feedstock for C4 from the refining-1 process of an upstream butadiene plant, can also undergo feed pretreatment. The unsaturated refining-1 C4 feedstock from the countercurrent BD plant can be filtered and then washed in a water wash column using a controlled flow of demineralized wash water to remove most water-soluble impurities, such as nitrites. The top of the water wash column can be equipped with a mesh pad to merge and remove unseparated water. The spent wash water from the bottoms of the columns can be sent to a wastewater system for further treatment. The washed C4 mixture can be taken from above the wash water column and sent under pressure control to the feed compensation drum of train 2 C4. The compensation drum can also be equipped with a smelter and a water boot to remove any remaining free water. Should a small amount of non-condensable vapors accumulate in the compensation drum, a pressure vent system with an associated nitrogen purge can be provided to dilute and vent these vapors to the flare. The washed C4 feedstock can then be pumped from the compensation drum and sent to the primary reactor of train 2. FCC / RFCC reaction system In some embodiments, the FCC / RFCC reaction system includes reactors for the selective conversion of isobutene to methyl ether (re-b) by reaction with methanol. In other embodiments, the FCC / RFCC reaction system includes reactors for the selective dimerization of isobutene to form isooctene, in which oxygenated compounds such as methanol can be used as selecting agents. For example, the treated mixed C4 olefin feed from the C4 feed compensation drum of train 1 can be mixed with recycled oxygenated compounds and fresh and recycled methanol (selection agents) and fed to a dimerization reactor, such as a water-cooled, tempered primary tubular reactor (WCTR). The mixed feed stream can be preheated using a low-pressure (LP) steam preheater. The process fluid then passes through the catalyst-filled tube side of the WCTR. The dimerization of isobutylene to isoctene takes place in the primary DIB (diisobutylene) WCTR under relatively low temperature conditions. The heat of reaction can be removed by a closed-loop warm water system provided on the shell side of the WCTR. Train 1 Debuting Column The effluent from the primary WCTR can then feed a debutanizer column under pressure control. The effluent can be heated through a feed debutanizer column / bottom heat exchanger before entering the debutanizer. The overhead vapor from the debutanizer (primarily C4 and methanol) is cooled, condensed, and the condensate is collected in the overhead drum of the debutanizer column. The distillate from the overhead drum is pumped under level control from the drum. A portion of the distillate is returned to the debutanizer column as reflux, and the net distillate flow can be preheated through an LP steam preheater and then sent to a secondary WCTR reactor. The bottoms stream from the debutanizer is cooled through the debutanizer feeder / bottoms exchanger and then sent to a separator column, which is discussed later. Train 1 Secondary reactor DIB (Disobutylene) The distillate stream from the debutanizer column is combined with the oxygenate recycle, cooled via a feed cooler, and fed to the inlet of a secondary water-cooled tubular reactor (WCTR) to enable further conversion of isobutylene to isooctene and other C8 olefins. Isobutylene dimerization again takes place in the secondary WCTR under low-temperature conditions. The heat of reaction is also removed by circulating water through the shell side of the reactor using a warm water system. Train 1 Reaction Column CD The effluent from the secondary WCTR flows to the CD reaction column via a CD reaction column feeder / bottom heat exchanger. The CD reaction column operates similarly to a conventional distillation column and is equipped with an external reboiler and an overhead condenser. The CD reaction column also contains trays above and below the feed inlet nozzle. CD modules (structured catalyst carriers containing catalysts) are also located in beds above the feed nozzle. The CD modules facilitate both the reaction and the simultaneous distillation and separation of the reaction product and heavier (C8+) hydrocarbons from unreacted C4 hydrocarbons, along with MTBE and other oxygenated compounds. Along with other C4 hydrocarbons, unreacted isobutylene is distilled through reaction column CD from the feed point to the reaction zone within the CD modules for isobutylene conversion. The unreacted C4 hydrocarbons, along with excess methanol and light impurities in the feed, exit the column as an overhead distillate. The distillate is cooled, condensed, and the condensate is collected in the elevated drum of reaction column CD. The distillate from the elevated drum is pumped under level control from the drum. A portion of the distillate is returned to reaction column CD as reflux, and the net distillate flow is cooled and sent to a methanol extraction column in train 1 for the removal of excess methanol. Isooctene (DIB), C8 hydrocarbons, and other heavier hydrocarbons, along with oxygenates, exit the CD reaction column as bottom product. This bottom product is cooled via the CD reaction column feeder / bottom heat exchanger and then sent to the DIB / MTBE separator column for the separation and recovery of oxygenates, which are used as screening agents in the main reactor section. Any oxygenates purged from the DIB / MTBE separator are sent to OSBL for blending into the engine gasoline pool (Mogas). Reactor Train 2 In some embodiments, the C4 reaction system of the steam cracker includes reactors for the selective conversion of isobutene to methyl tert-butyl ether via reaction with methanol. In other embodiments, the FCC / RFCC reaction system includes reactors for the selective dimerization of isobutene to form isooctene, in which oxygenated compounds such as methanol can be used as selecting agents. When producing dimers, train 2 may include a DIB (diisobutylene) primary reactor. The treated mixed C4 olefin feed (raffinate-1) from the train 2 C4 feed compensation drum may be mixed with recycled oxygenated compounds and fresh and recycled methanol (selection agents). Before entering the water-cooled warmed tubular primary reactor (WCTR), the mixed feed stream may be preheated by an LP steam preheater. The process fluid then passes through the catalyst-filled tube side of the WCTR. The dimerization of isobutylene to isoctene takes place in the primary DIB (diisobutylene) WCTR under relatively low temperature conditions. The heat of reaction is removed by a closed-loop warm water system provided on the shell side of the WCTR. Train 2 Debuting Column The effluent from the primary WCTR of train 2 is then fed to the debutanizer column of train 2 under pressure control. The effluent is heated via the CD reaction column feeder / bottom heat exchanger before entering the debutanizer. The debutanizer's overhead vapor (primarily C4s and methanol) is cooled, condensed, and the condensate is collected in the debutanizer column's overhead drum. The distillate from the overhead drum is pumped under level control from the drum. A portion of the distillate is returned to the debutanizer column as reflux, and the net distillate stream is preheated through an LP steam preheater and then sent to the secondary WCTR reactor of train 2. The debutanizer bottoms stream from train 2 can be cooled via a debutanizer feeder / bottoms heat exchanger and then sent to the MTBE / DIB separator column under flow control. Train 2 Secondary reactor DIB (Diisobutylene) The distillate stream from the debutanizer column of train 2 is combined with the oxygenate recycle and fed to the inlet of a secondary water-cooled tubular reactor (WCTR) of train 2 to allow further conversion of isobutylene to isooctene and other C8 finites. The dimerization of isobutylene takes place again in the secondary WCTR under low-temperature conditions. MTBE CD reaction column of train 2 (including CDHydro functionality) The effluent from the secondary WCTR flows to a train 2 reaction column CD via the CD reaction column feeder / bottom heat exchanger. The reaction column CD operates similarly to a conventional distillation column and is equipped with an external reboiler and an overhead condenser. The reaction column CD also contains trays above and below the feed inlet nozzle. CD modules (structured catalyst carriers containing catalysts) are also located in beds above the feed nozzle. The CD modules in the CD reaction column of train 2 can facilitate both reactions (selective hydrogenation and isobutylene dimerization) as simultaneous distillation and separate the reaction product and heavier hydrocarbons (C8+) from unreacted C4 hydrocarbons along with MTBE and other oxygenated compounds. For train 2, the CD reaction column is equipped with two types of CD modules. The first type of CD module provides catalysts to support the continuous dimerization of isobutylene to C8. The second type of CD module provides catalysts for the selective hydrogenation of butadienes. These CD modules provide the unique functionality of CDHydro. Hydrogenation also requires the injection of a small amount of fresh hydrogen into the CD reaction column. In the CDHydro section, three types of chemical reactions occur: Hydrogenation of butadiene to n-butenes, hydroisomerization of n-butenes between 1-butene and 2-butene, and olefin saturation. Olefin saturation can be minimized by using highly selective catalysts and due to the high reactivity of butadiene relative to olefins. Selective hydrogenation is an exothermic process and therefore causes a temperature increase throughout the reactor. The heat of reaction is absorbed by the reflux from column CD as it flows down through the CD modules. Along with other C4 hydrocarbons, unreacted isobutylene and butadiene are distilled through the reaction column CD from the column feed point to the reaction zone within the CD modules for isobutylene conversion and diene saturation. The unreacted C4 hydrocarbons, along with excess methanol and light impurities in the feed, are recovered from the column as top distillate. The distillate is cooled, condensed, and the condensate is collected in the elevated drum of reaction column CD in train 2. The distillate from the elevated drum is pumped under level control from the drum. A portion of the distillate is returned to reaction column CD as reflux, and the net distillate flow is cooled and sent to a methanol extraction column for the removal of excess methanol. Non-condensable fractions are periodically vented from the elevated drum via a remote valve HC. Isooctene (DIB, Dimer8), C8 olefins, and other heavier hydrocarbons, along with oxygenated compounds, exit the CD reaction column as bottom product. This bottom product can be cooled via the CD reaction column / bottom heat exchanger feeder and then sent to the DIB / MTBE separator column for the separation and recovery of oxygenated compounds, which will be used as screening agents in the main reactor section. A portion of the oxygenated compounds purged from the DIB / MTBE separator overhead can be sent for blending in the Mogas pool. Common methanol recovery section Dimer8 (reaction trains 1 and 2) The C8 distillate streams from the CD reaction columns in trains 1 and 2 (containing a mixture of C4 hydrocarbons and methanol) are first treated separately in the methanol extraction columns of train 1 and train 2, as described above. Methanol can be scrubbed from each of the C8 distillate streams using countercurrent flows of demineralized water. Each of the methanol extraction columns can be equipped with mesh pads at the top of the columns to prevent water carryover. The scrubbed C8 hydrocarbons are taken from the top of each of trains 1 and 2 to provide the individual raffinate-2 streams. The raffinate-2 wash from the Methanol Extraction Column of train 1 is then fed to the Isobutane Purification Section. The raffinate-2 wash from the methanol extraction column of train 2 is then fed to the 1-butene recovery and purification section.The aqueous extract streams (bottoms) from the methanol extraction columns of train 1 and train 2 are combined and sent to the common methanol recovery column for methanol and water separation by distillation. The vapor from the common methanol recovery column is cooled, condensed, and the condensate is collected in the methanol recovery column's overhead drum. The distillate from the overhead drum is pumped under level control. A portion of the distillate is returned to the methanol separation column as reflux, and the net distillate stream (purified methanol) is recycled back to the primary and secondary reactors of reaction train 1 and train 2 and to reaction columns CD. Fresh makeup methanol can also be added to the overhead drum. The wash water from the methanol recovery column bottoms is recycled back to the methanol extraction columns of train 1 and train 2 for reuse. Common Dimer8 DIB / oxygen separator column The bottom streams from the CD reaction column and debutanizer of the Dimer8 reaction train 1 and train 2 may contain oxygenated compounds such as TBA, MTBE, MSBE, and C9 ethers, which are removed in the DIB / oxygen separator column. These bottom streams from train 1 and train 2 are combined and fed to a single DIB / oxygenated compounds column. In the DIB / oxygenated compounds column, most of the lighter oxygenated compounds (MTBE, MSBE, and TBA) are distilled upwards in the vapor phase and then condensed from above. The overhead vapor is cooled with water, condensed in the separator condenser, and the condensate is collected in the oxygenator / dib separator overhead drum. The distillate from the elevated drum is pumped back, and a portion of it is returned to the MTBE / DIB separator column as reflux. Most of the oxygenate purge from the column is pumped back and blended with the unit feedstock for use as screening agents in the primary and secondary reactors of Dimer8 reaction train 1 and train 2. A smaller portion of the distillate is sent as an oxygenate purge for blending in the Mogas pool. The separator bottoms stream consists of isooctane (DIB), other C8 olefins, and C12, C16, and C9 ethers. This bottoms stream is then sent to the C8 saturation section to produce isooctane. Common isooctene saturation MA / IZ / ¿U¿¿ / U41100 If desired, the isooctene recovered from the separator bottom stream can be hydrogenated to form isooctane. Purification of 1 / 2 butane (Refining-2 of train 1) The raffinate-2 stream from reaction train 1 is combined with the raised product from light column B1 (see procedure description for 1-butene separation unit below) and sent to the 1-butane purification section. The combined feedstock from Refined 2 is first fed to the deisobutanizer column. The deisobutanizer removes isobutane and light hydrocarbons from the remaining C4 in Refined 2. The net condensate flow from the deisobutanizer column is then fed to the DME light column. The bottom stream from the DME light column is recovered as the bottom product, which may include 2-butene and n-butane. DME Lightweight Column The net overhead flow from the deisobutanizer column is then fed to the DME light column. The DME light column removes light oxygenated compounds (such as DME) and other light hydrocarbons from the high-purity isobutane product. The overhead flow from the deisobutanizer column can be preheated via the DME light column feed / effluent heat exchanger before being fed to the DME light column. The vapor rising from the DME light column is cooled, condensed, and the condensate is collected in the DME light column's riser drum. A portion of the distillate is returned to the DME light column as reflux, and the net distillate flow (DME and other light hydrocarbons) is recovered as DME light product. The bottom stream from the DME light column is cooled via the DME light column feeder / DME light column effluent exchanger, further cooled via the isobutane product cooler, and then sent to the battery boundaries as high-purity isobutane product. In some embodiments, the recovered isobutane stream can have a purity of at least 99 wt%. In other embodiments, the recovered isobutane stream can have a purity greater than 99.2 wt, greater than 99.3 wt, greater than 99.4 wt, or even greater than 99.5 wt. Separation of 1-Butene (Raffinate-2 from train 2) The raffinate-2 from reaction train 2 is fed to the combined heavy B1 and light B1 columns to separate and purify the 1-butene product from the remainder of the raffinate-2 feed. The raffinate-2 from Dimer8 reaction train 1 is first fed to the heavy B1 column. The compressed overhead stream from heavy column B1 is partially condensed via the reboiler for heavy column B1. The condensate is then cooled and collected in the reflux drum of heavy column B1. The condensate from the reflux drum is pumped out, and a portion of it is returned to heavy column B1 as reflux. The net condensate flow then feeds light column B1. The bottom stream from the heavy column B1 is pumped to the battery limits and provides a refined product-3. Lightweight column section The net condensate flow from the reflux drum of heavy column B1 is pumped to the light column B1 section for further separation and purification of 1-butene. The compressed overhead stream from light column B1 is partially condensed via the reboiler for light column B1, and the condensate is then cooled with water and collected in the reflux drum of light column B1. The condensate from the reflux drum is pumped out, and a portion of it is returned to light column B1 as reflux. The net condensate flow (rich in isobutane) is then combined with raffinate-2 from train 1 and processed in the Isobutane Purification Section, as described above. The bottom stream from the B1 light column is the high-purity 1-butene product. In some embodiments, the recovered 1-butene stream can have a purity of at least 99 wt%. In other embodiments, the recovered 1-butene stream can have a purity greater than 99.2 wt, greater than 99.3 wt, greater than 99.4 wt, or even greater than 99.5 wt. As described above, the embodiments in this dissertation can provide the efficient co-production of both high-purity 1-butene and high-purity isobutane. The compositions of the initial mixed C4 streams are advantageously utilized, with partial common processing where beneficial, to produce high-purity products. Maintaining the reaction trains and water wash as separate systems enables the production of high-quality, high-purity isobutane and 1-butene streams. Although this disclosure describes a limited number of embodiments, those skilled in the art, benefiting from this disclosure, will appreciate that other embodiments can be devised without departing from the scope of this disclosure. Accordingly, the scope is limited only by the appended claims.

Claims

1. A process for co-producing high-purity isobutane and high-purity 1-butene streams, the process comprising: providing a first C4 mixed stream and a second C4 mixed stream, each comprising isobutene, isobutane, 1-butene, and 2-butene, wherein the first C4 mixed stream has a higher isobutane concentration than the second C4 mixed stream; feeding the first C4 mixed stream and methanol, as a reagent or selecting agent, to a first reaction system for converting the isobutene contained therein into methyl tert-butyl ether or isobutene dimers; feeding the second C4 mixed stream and methanol, as a reagent or selecting agent, to a second reaction system for converting the isobutene contained therein into methyl tert-butyl ether or isobutene dimers;separating an effluent from the first reaction system in a first separation system, including a water scrubbing system, to recover a first light hydrocarbon stream comprising 1-butene, 2-butene, isobutane, a first methanol + water stream, and a first heavy hydrocarbon stream comprising methyl tert-butyl ether or isobutene dimers; separating an effluent from the second reaction system in a second separation system, including a water scrubbing system, to recover a second light hydrocarbon stream comprising 1-butene, 2-butene, and isobutane, a second methanol + water stream, and a second heavy hydrocarbon stream comprising methyl tert-butyl ether or isobutene dimers; feeding the first and second methanol + water streams to a methanol recovery system to separate the methanol from the water and return at least a portion of the methanol to one or both of the first and second reaction systems;feeding the second light hydrocarbon stream to a separation system to recover a stream containing isobutane, a stream of 1-butene, and a first stream of heavy C4 hydrocarbons comprising n-butanes and 2-butene; feeding the stream containing isobutane and the first light hydrocarbon stream to a separation system to recover a stream of isobutane and a second stream of heavy C4 hydrocarbons comprising n-butanes and 2-butene.

2. The process of claim 1, further comprising separating the dimethyl ether from the isobutane stream.

3. The process of claim 1, wherein the isobutane stream has a purity of at least 99% by weight and wherein the 1-butene stream has a purity of at least 99% by weight.

4. The process of claim 1, further comprising feeding a hydrocarbon stream to a fluid catalytic cracking process or a residual fluid catalytic cracking process and recovering the first mixed C4 stream, wherein the first mixed C4 stream has an isobutane concentration of at least 20% by weight.

5. The process of claim 4, further comprising feeding a hydrocarbon stream to a steam cracking process and recovering the second mixed C4 stream, wherein the second mixed C4 stream has an isobutane concentration of less than 5% by weight.

6. The process of claim 5, wherein the first mixed stream of C4 has an isobutene concentration of less than 25% by weight, and wherein the second mixed stream of C4 has an isobutene concentration of at least 30% by weight.

7. A system for the co-production of a high-purity isobutane stream and a high-purity 1-butene stream, the system comprising: a first C4 mixed stream and a second C4 mixed stream, each comprising isobutene, isobutane, 1-butene, and 2-butene, wherein the first C4 mixed stream has a higher isobutane concentration than the second C4 mixed stream; a first methanol stream and a second methanol stream; a first reaction system configured to receive the first C4 mixed stream and the first methanol stream and to react the first C4 mixed stream and methanol, as a reagent or selecting agent, converting the isobutene contained therein into methyl tert-butyl ether or isobutene dimers;a second reaction system configured to receive the second mixed stream of C4 and the second stream of methanol and to react the second mixed stream of C4 and methanol, as a reagent or selecting agent, converting the isobutene contained therein into methyl tert-butyl ether or isobutene dimers; a first separation system, including a water washing system, for separating an effluent from the first reaction system to recover a first light hydrocarbon stream comprising 1-butene, 2-butene, isobutane, a first methanol+water stream, and a first heavy hydrocarbon stream comprising methyl tert-butyl ether or isobutene dimers;a second separation system, including a water washing system, for separating an effluent from the second reaction system to recover a second light hydrocarbon stream comprising 1-butene, 2-butene, isobutane, a second methanol+water stream, and a second heavy hydrocarbon stream comprising methyl tert-butyl ether or isobutene dimers; a common methanol recovery system for receiving the first and second methanol+water streams to separate the methanol from the water, and a flow line for returning at least a portion of the methanol to one or both of the first and second reaction systems; a first light hydrocarbon separation system for receiving the second light hydrocarbon stream and recovering a stream containing isobutane, a 1-butene stream, and a first C4 heavy hydrocarbon stream comprising n-butanes and 2-butene;a second light hydrocarbon separation system to receive the first light hydrocarbon stream and to recover an isobutane stream and a second heavy C4 hydrocarbon stream comprising n-butanes and 2-butene.; 8. The system of claim 7, further comprising a first mixer for mixing the first and second heavy hydrocarbon streams of C4, and a second mixer for mixing the first and second heavy hydrocarbon streams.

9. The system of claim 7, wherein each of the first and second reaction systems is configured to produce isobutene dimers.

10. The system of claim 7, wherein each of the first and second reaction systems is configured to produce useful methyl te re-b ether.

11. The system of claim 7, wherein the first reaction system includes a fixed bed reactor, or two or more fixed bed reactors in series or in parallel, followed by a catalytic distillation reactor.

12. The system of claim 7, wherein the second reaction system includes a fixed bed reactor, or two or more fixed bed reactors in series or in parallel, followed by a catalytic distillation reactor.

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